The present application is a continuation application of PCT/JP01/09931 filed on Nov. 14, 2001, claiming priority from a Japanese patent application No. 2000-371638 filed on Dec. 6, 2000, the contents of which are incorporated here in by reference.
1. Field of the Invention
The present invention relates to an electron beam exposure system and an electron lens.
2. Description of the Related Art
FIG. 1 is a cross sectional view showing a multi-axis electron lens 350 in a conventional electron beam exposure system. In the multi-axis electron lens 350, a plurality of electron beams 320 are focused independently using two magnetic conductors 330 which include a lens coil 310 and a plurality of apertures 320.
However, since a magnetic field 340 formed in the plurality of apertures 320 by one lens coil 310 does not become symmetrical to medial axes of the apertures 320, it is difficult to focus the plurality of electron beams, which pass through the apertures 320 respectively, on predetermined positions.
Accordingly, it is an object of the present invention to provide an electron beam exposure system and an electron lens which can solve the foregoing problem. The object can be achieved by combinations described in the independent claims. The dependent claims define further advantageous and exemplary combinations of the present invention.
In order to solve the foregoing problem, according to the first aspect of the present invention, there is provided an electron beam exposure system for exposing a pattern on a wafer by a plurality of electron beams, in which the system includes: an electron beam generating section for generating the plurality of electron beams; an electron lens section with a plurality of apertures through which the plurality of electron beams pass, for independently focusing the plurality of electron beams; and a first magnetic field formation section, which is provided in at least one of the plurality of apertures, for forming a magnetic field in a direction substantially perpendicular to an irradiation direction of the electron beams passing through one of the plurality of apertures.
In the electron beam exposure system the first magnetic field formation section may be provided on a wall of one of the plurality of apertures.
The first magnetic field formation section may include a coil for forming a magnetic field and an insulating member provided between the coil and the wall of the aperture.
The first magnetic field formation section may includes: a plurality of first magnetic field formation sections, which are provided in the plurality of apertures; and a coil control section for independently controlling current supplied to each of the plurality of first magnetic field formation sections.
The coil control section may independently control current supplied to each of the plurality of first magnetic field formation sections based on position of each of the plurality of apertures in which each of the plurality of first magnetic field formation sections is provided.
The coil control section may control the current so that current supplied to a part of the plurality of magnetic field formation sections provided in first apertures of the plurality of apertures is higher than current supplied to another part of the plurality of magnetic field formation sections provided in second apertures of the plurality of apertures, where the second apertures are located outside of the first apertures in the electron lens section.
The electron beam exposure system may further include a second magnetic field formation section provided in a position for forming magnetic field in a direction substantially perpendicular to the direction of the magnetic field formed in the aperture by the first magnetic field formation section.
The electron beam exposure system may further include a coil control section for independently controlling the current supplied to the first magnetic field formation section and current supplied to the second magnetic field formation section.
The electron beam exposure system may further include a third magnetic field formation section and a fourth magnetic field formation section, which are provided in an opposite side of the first magnetic field formation section and the second magnetic field formation section respectively.
In the electron beam exposure system according to the invention, the electron lens section may include: a first magnetic conductor with a plurality of apertures through which the plurality of electron beams pass; a second magnetic conductor with a plurality of apertures through which the plurality of electron beams pass; wherein the second magnetic conductor is provided substantially parallel with the first magnetic conductor; the first magnetic field formation section is provided in the apertures of the first magnetic conductor, and the electron beam exposure system further comprises a fifth magnetic field formation section provided in the apertures of the second magnetic conductor.
The electron beam exposure system may further include a cooling section for cooling the first magnetic conductor and the second magnetic conductor.
The electron beam exposure system may further include: a substrate, which is provided substantially in parallel with the electron lens section, including wiring in which the current to the first magnetic field formation section flows; and a wire section for connecting the first magnetic field formation section and the wiring.
According to another aspect of the invention, an electron lens for independently focusing a plurality of electron beams, includes: a first magnetic conductor with a plurality of apertures through which the plurality of electron beams pass; a second magnetic conductor with a plurality of apertures through which the plurality of electron beams pass, wherein the second magnetic conductor is provided substantially parallel with the first magnetic conductor; and a magnetic field formation section, which is provided in at least one aperture of the plurality of first apertures and the plurality of second apertures, for forming a magnetic field in a direction substantially perpendicular to an irradiation direction of the electron beams passing through the apertures.
According to a third aspect of the invention, an electron beam exposure system for exposing a pattern on a wafer by a plurality of electron beams, includes: an electron beam exposure apparatus; comprising: an electron beam generating section provided at one end of the electron beam exposure apparatus; a wafer stage provided at the other end of the electron beam exposure apparatus, and opposing to the electron beam generating section; at least one shaping member provided between the electron beam generating section and the wafer stage, including a plurality of apertures having predetermined shapes, each of the apertures having an axis extending in a direction substantially parallel with an irradiation direction of the electron beams; and at least one electron lens section provided between the electron beam generating section and the wafer stage, and positioned either upstream or downstream of the shaping member in the irradiation direction of the electron beams, the electron beam generating section includes: a plurality of apertures with an axis extending in a direction substantially parallel with the irradiation direction of the electron beams; and at least one magnetic field formation section provided at each of the plurality of apertures, the magnetic field formation section being symmetrical with respect to the axis of the aperture of the electron lens section.
According to a fourth aspect of the invention, an electron lens used for an electron beam exposure system for exposing a pattern on a wafer by a plurality of electron beams, includes: a plurality of apertures with an axis extending in a direction substantially parallel with the irradiation direction of the electron beams; and at least one magnetic field formation section provided at each of the plurality of apertures, the magnetic field formation section being symmetrical with respect to the axis of the aperture of the electron lens section.
This summary of invention does not necessarily describe all necessary features so that the invention may also be a sub-combination of these described features.